Travel Time and Congestion
Description:
Congestion results when the traffic infrastructure lags behind the growth in an area and increases the time it takes to complete a trip by car. The travel time index and the annual delay per commuter measure the effect of congestion on the amount of time it takes us to travel through the city. Congestion results in excess fuel consumption and increased costs, both in the expense of the fuel and in the value of the driver's time. Congestion tends to be worse in larger urban areas than smaller ones; however, smaller urban areas may contain pockets of traffic congestion that are just as bad as those found in larger areas. Increased infrastructure, both in the form of new roads and increased public transportation, can help to alleviate congestion.
Data Source:
Data were collected in January 2012 by Arizona State University's Decision Center for a Desert City (DCDC) from the 2011 Urban Mobility Report, The Mobility Data for Phoenix, AZ and The Mobility Data for Tucson, AZ.
Data Quality Comments:
Travel Time Index: A measure of congestion that focuses on each trip and each mile of travel. The ratio of travel time in the peak period to travel time in free-flow. A value of 1.30 indicates a 20-minute free-flow trip takes 26 minutes in the peak.
Annual Delay per Commuter: A yearly sum of all the per-trip delays for those persons who travel in the peak periods (6 to 10 a.m. and 3 to 7 p.m.). This measure illustrates the effect of the per-mile congestion as well as the length of each trip.
Excess Fuel Consumed: Increased fuel consumption due to travel in congested conditions rather than free-flow conditions.
Congestion Cost: Value of travel delay for 2010 (estimated at $16.30 per hour of person travel and $88.12 per hour of truck time) and excess gasoline consumption (passenger vehicles) and diesel (trucks) estimated using state average cost per gallon.
Note: The congestion estimates for all study years are recalculated every time the methodology is altered to provide a consistent data trend. The estimates and methodology from this report should be used in place of any other previous measures. (Appendix A of the 2011 Urban Mobility Report).
Disclaimer from The 2011 Urban Mobility Report: The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the U.S. Department of Transportation University Transportation Centers Program in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof.
Average Commute Time
Visualization Notes:
Data show the mean travel time (in minutes) to work of workers 16 years and over who did not work at home. Data were updated in January 2012 by Arizona State University's Decision Center for a Desert City (DCDC) from the U.S. Census Bureau's American Community Survey, 2002-2010, one-year estimates, Table GCT 0801, Mean Travel Time to Work.
Travel Time Index
Visualization Notes:
The travel time index is the ratio of travel time in the peak period to the travel time at free-flow conditions. A value of 1.30 indicates a 20-minute free-flow trip takes 26 minutes in the peak. Travel time is increasing in Phoenix due to increases in congestion, although Tucson has shown a downward trend in recent years.
Annual Hours of Delay Per Peak Traveler
Visualization Notes:
The annual delay per commuter is yearly sum of all the per-trip delays for those persons who travel in the peak periods (6 to 10 a.m. and 3 to 7 p.m.). This measure illustrates the effect of the per-mile congestion as well as the length of each trip. Tucson, who once lagged far behind Phoenix in annual delay, has increased their annual delay per traveler at a faster rate than Phoenix, narrowing the gap between the two cities; however, both cities have shown declines in the annual delay since peaking in 2005.
Annual Excess Fuel Consumed Per Traveler
Visualization Notes:
Congestion results in wasted fuel, resulting in costs for individual travelers that add up to millions of lost dollars for a metropolitan area. Excess fuel consumed is defined as the increased fuel consumption due to travel in congested conditions rather than free-flow conditions. Phoenix drivers consume much more excess fuel than their Tucson counterparts due to higher congestion in the Valley.
Annual Cost of Congestion Per Traveler
Visualization Notes:
Congestion cost is the value of travel time delay (in 2010 estimated at $16.30 per hour of person travel and $88.12 per hour of truck time) and excess gasoline consumption (passenger vehicles) and diesel (trucks) estimated using state average cost per gallon. This cost has decreased in recent years in both Phoenix and Tucson.
Data Source
Data were collected in January 2012 by Arizona State University's Decision Center for a Desert City (DCDC) from the 2011 Urban Mobility Report, The Mobility Data for Phoenix, AZ and The Mobility Data for Tucson, AZ.
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